Medium and high-throughput assays (i.e., screens) have generally not been applied to mammalian neurons because of the difficulties in culturing them in large numbers and because of the low efficiency with which the genetic makeup of neurons can be altered. Furthermore, because many aspects of neuronal function can only be assayed with electrophysiological assays, follow-up analysis and validation of screening hits is difficult. We propose to use automated imaging approaches to analyze synapse number and neuronal structure in vitro in a scalable format. We have implemented tissue culture and immunostaining approaches to monitor the number and types of synapses formed onto neurons in multi-well plates. We will couple this analysis with lentivirus mediated introduction of short-hairpin RNAs to induce RNA interference against genes expressed in neurons. This will be performed in concert with transcriptional analysis of neurons to determine the key changes in gene expression that correlate with structural and synaptic changes. The proposal represents a significant collaboration between several groups with expertise in functional analysis of neurons, automated analysis of images, viral mediated manipulation of gene expression, and whole-genome transcriptional analysis. We hope that our work will lead, for the first time, to a turn-key and robust method of analysis of neuron and synapse structure suitable for scalable, whole-genome analysis. Such a system will permit the unbiased and systematic analysis of pathways involved in neuropsychiatric diseases including neurodegenerative diseases such as Alzheimer's and Parkinson's as well as neurodevelopmental disorders such as mental retardation and autism.